Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaptions (Details)

v3.21.1
Derivative Instruments and Hedging Activities Schedule of Interest Rate Swaptions (Details) - USD ($)
 3 Months Ended
Mar. 31, 2020
Mar. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Derivative [Line Items]        
Notional $ 60,549,307,000 $ 19,137,094,000 $ 23,932,603,000 $ 48,445,497,000
Interest Rate Swaption [Member] | Long [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Cost Basis     (7,210,000)  
Fair Value     2,448,000  
Weighted Average Remaining Maturity 4 months 7 days      
Interest Rate Swaption [Member] | Long [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Cost Basis     (3,010,000)  
Fair Value     0  
Weighted Average Remaining Maturity 29 days      
Interest Rate Swaption [Member] | Short [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Cost Basis     (2,600,000)  
Fair Value     3,044,000  
Weighted Average Remaining Maturity 5 months 4 days      
Underlying Swap [Member] | Long [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Weighted Average Remaining Maturity 10 years      
Notional     $ 2,800,000,000  
Underlying Swap [Member] | Long [Member] | Variable Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate        
Derivative [Line Items]        
Weighted Average Fixed Interest Rate     1.32%  
Underlying Swap [Member] | Long [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Weighted Average Remaining Maturity 10 years      
Notional     $ 2,000,000,000  
Weighted Average Fixed Interest Rate     0.23%  
Underlying Swap [Member] | Short [Member] | Fixed Income Interest Rate [Member] | Less Than Six Months Remaining Maturity [Member]        
Derivative [Line Items]        
Weighted Average Remaining Maturity 10 years      
Notional     $ 1,050,000,000  
Weighted Average Fixed Interest Rate     0.55%